Single-rod shifting device for an automobile manual transmission

ABSTRACT

The single-rod shifting device for a motor vehicle manual transmission, in particular for a six-speed transmission, has a central shifting shaft, fork-shaped shifting elements that engage into sliding bushings, and a locking device. The locking device is equipped with a lever ( 3, 11 ) whose rotation point lies on the rotation axis of the axially displaceably mounted central shifting shaft ( 1 ) and which is joined to it via a radial entrainment arrangement. Also provided is a blocking part ( 5 ) that is arranged immovably in the housing in the shifting direction, as well as a coupling drive that converts the rotation of the lever into a linear motion of the blocking elements ( 15, 15 ′ . . . ) on the shifting elements and on the blocking part ( 5 ) ensure that upon superposition of the blocking elements in the shifting direction, a shifting of the shifting elements is prevented.

The present invention concerns a single-rod shifting device for a motorvehicle manual transmission, in particular for a six-speed transmission,having a central shifting shaft, having fork-shaped shifting elements inthe form of shifting links or thrust forks that engage into slidingbushings, and having a locking device which, upon shifting of one of theshifting elements out of the neutral position into a shifting position,locks in their neutral positions the shifting elements that are not tobe shifted.

A single-rod shifting device for a motor vehicle manual transmissionhaving fork-shaped shifting links, engaging into sliding bushings, thatcan be pivoted by at least one shifting shaft about parallel pivotbearings out of their neutral position into shifting positions, in whichcontext locking means arranged in stationary fashion in the transmissionhousing coact with locking grooves that are configured in locking linkssecured to the shifting links in such a way that upon pivoting of oneshifting link into a shifting position, the other shifting links arelocked in their neutral position, is known from the Applicant's DE-A 4017 957. In this, a two-armed rocker arm mounted parallel to the pivotbearing in the transmission housing is arranged in each case between theshifting links, and engages into the locking grooves via end-locatedblocking cams.

Locking of the shifting links is thus accomplished in this context bymeans of a rocker-arm and coupling-member system which does not lock theshifting links that are not to be shifted until shifting of a ratio intothe selected gate occurs. The lever system comprises three members ifthree shifting links are provided. In the case of a pure link shiftingsystem, increasing the number of gear ratios in the transmission alsoincreases the number of shifting links, depending on the gear setconfiguration. If the locking principle were retained, this wouldrequire two additional members in the lever system for each additionalshifting link. This makes the system complex, difficult to assemble, andsensitive to tolerances; it acts indirectly and is therefore notpositive.

A manually shifted transmission for a motor vehicle transmission havinga shifting shaft which allows the transmission ratios to be preselectedsuccessively by means of its rotation and to be shifted by means of itslongitudinal displacement, is known from EP B 530 466. Provided in thisis a blocking element, immobilized with the shifting shaft in itslongitudinal direction, with which the transmission ratios that are notto be shifted can be locked, the blocking element being a blocking shaftmounted parallel to the shifting shaft, and an entrainment pin of theshifting shaft being longitudinally guided in a gated guide of theblocking shaft in order to transfer the rotary motion. The shiftingshaft comprises shifting sleeves on which are rotatably mounted forksleeves, on which the shifting forks engaging into synchronizercouplings of the transmission ratios are arranged; in order to shift thegear ratios, radially projecting claws of the shifting sleeves restagainst the end faces of the fork sleeves, and the claws engage intoannular cutouts of the fork sleeves that are not to be actuated.

It is the object of the present invention to create a single-rodshifting device for a motor vehicle manual transmission, in particularfor a six-speed transmission, whose locking device is configured in sucha way that the shifting elements that are not to be shifted are alreadylocked upon selection of the shift gate, i.e. before the ratio to beshifted is inserted into the selected shifting gate; which is of simpleconfiguration, comprises few parts and thus is easy to assemble; whichis configured in terms of function independently of the number ofshifting elements and requires little installation space; which lockssecurely and nevertheless enables good diagonal shiftability; which haslow moving masses and low frictional losses, so that there is littleinfluence on selection and shifting forces; and in which the selectionof a further ratio is prevented in every case in which a ratio isalready selected, and which is economical to manufacture.

Proceeding from a single-rod shifting device of the kind described inmore detail above, this object is achieved with the features indicatedin the characterizing portion of claim 1; advantageous embodiments aredescribed in the dependent claims.

What is therefore provided according to the present invention is that byway of a radial entrainment, the rotary selection motion of the axiallydisplaceably mounted central shifting shaft is transferred to a leverwhose rotation point lies on the rotation axis of the central shiftingshaft; that by means of a coupling drive, the rotary motion of the leveris converted into a linear motion of a blocking part transversely to theshifting direction of the central shifting shaft, the blocking partbeing arranged immovably with respect to the housing in the shiftingdirection; that the relative motion of the central shifting shaftrelative to the blocking part upon shifting of a ratio is accomplishedby way of a corresponding degree of freedom in the radial entrainmentitself or within the coupling drive; and that the blocking part and theshifting links or thrust forks have blocking elements which are arrangedin such a way that upon superposition of the blocking elements in theshifting direction, a motion of the shifting links or thrust forks toshift the transmission ratios is prevented.

The particular advantage achieved thereby is that because of theconfiguration of the locking device according to the present invention,it is already activated upon selection of the gate, i.e., that theshifting elements which are not to be shifted are already locked beforethe ratio to be shifted is inserted into the selected gate.

The invention will be explained in further detail below with referenceto the drawings, in which advantageous exemplary embodiments aredepicted and in which:

FIG. 1 is a perspective view of the essential components of a single-rodshifting device according to the present invention;

FIG. 2 is a side view of the shifting device;

FIG. 3 is a section along line A—A in FIG. 2;

FIG. 4 is a plan view, rotated 90°, of the shifting device shown in FIG.1;

FIG. 5 is a section along line A—A of a further exemplary embodiment;

FIG. 6 is that section of another exemplary embodiment;

FIG. 7 is a perspective view of a further exemplary embodiment of asingle-rod shifting device according to the present invention; and

FIG. 8 is a perspective view of another exemplary embodiment accordingto the present invention.

Since shifting devices of this kind are familiar to those skilled in theart, only those components essential for an understanding of theinvention are depicted in the Figures; in the individual depictions,identical parts are labeled with identical reference characters.

The single-rod shifting device for the manual transmission comprises acentral shifting shaft 1 that is mounted rotatably and axiallydisplaceably in the transmission housing (not depicted). The lockingdevice comprises a blocking panel 5, two guide studs 6, a lever hub 3,an entrainment pin 4 (FIG. 3), and an immobilization pin 2. In theexemplary embodiment depicted, the blocking panel is equipped with fourcutouts 8, 8′, . . . , two guide sleeves, and a rigid thrust member 9,respectively arranged perpendicular to blocking panel 5. The blockingpanel itself is arranged parallel to central shifting shaft 1, and ismounted displaceably on the two guide studs 6 that are immovably joinedto the housing.

Rigid thrust member 9 possesses at its one end a stud 10 parallel toblocking panel 5.

A lever hub 3, which together with an extension part 11 forms a lever,is provided coaxially and displaceably with respect to central shiftingshaft 1; provided on the lower, free end of extension part 11 is anelongated hole 7 into which stud 10 of blocking panel 5 engages.

Lever hub 3 has on its inside diameter one or two continuous grooves 12,12′ (FIG. 3) into which entrainment pin 4, arranged transversely tocentral shifting shaft 1, engages. Located on the outside diameter oflever hub 3 is a curved cutout 13, extending transversely to centralshifting shaft 1, into which immobilization pin 2, mounted immovablywith respect to the housing, engages.

Arranged transversely to blocking panel 5 on shifting elements 14, 14′,. . . , which are configured as shifting links or thrust forks, areblocking elements 15, 15′, . . . which have longitudinal grooves 16,16′, . . . arranged at an offset from one another in the transversedirection.

Upon selection of a gate, i.e., by rotation of central shifting shaft 1,lever hub 3 is therefore rotated via entrainment pin 4. By way of thethrust-rotary joint arranged between lever hub 3 and rigid thrust member9 of blocking panel 5, the rotary motion is converted into alongitudinal motion, and blocking panel 5 is moved on its guide studs 6,6′ transversely to central shifting shaft 1 as a function of therotational position of the central shifting shaft.

Cutouts 8, 8′ in the blocking panel engage via blocking elements 15,15′on shifting links 14, 14′; in the regions between the individualshifting gates, the blocking surfaces on the cutouts are superposed onthe blocking surfaces of the blocking elements on all the shiftinglinks. Once the rotational travel for reaching a shifting gate has beencompleted, the blocking panel is then aligned with the correspondinglongitudinal groove of the blocking element of the shifting link whichshifts the ratio or ratios in the preselected shifting gate. Theshifting link or thrust fork is thus free in the longitudinal directionand can be shifted. In the case of all the other shifting links orthrust forks, the blocking surfaces on the blocking panel are superposedon the blocking surfaces on the blocking elements of the links, sincethe longitudinal grooves in the blocking elements are arranged at anoffset to one another corresponding to the selection rotational travel.These shifting links or thrust forks are thus immobilized.

In order to shift a gear ratio, central shifting shaft 1 is displaced inthe longitudinal direction relative to the housing and thus relative toblocking panel 5. The configuration of the locking system requires alever hub 3 that is stationary in the longitudinal direction. For thatpurpose, lever hub 3 is secured in the longitudinal direction viaimmobilization pin 2 that is immovable with respect to the housing. Uponrotation of central shifting shaft 1, however, lever hub 3 is guidedalong in its outer curved groove 13 on immobilization pin 2. Upondisplacement of the central shifting shaft, entrainment pin 4 slidesalong in longitudinal grooves 12, 12′ on the inside diameter of leverhub 3.

In the exemplary embodiment depicted in FIG. 5, the thrust-rotary jointbetween lever 3, 11 and rigid thrust member 9 of blocking panel 5 isequipped not with stud 10 but with a plain-bearing- orneedle-bearing-mounted roller 17. Frictional losses in the thrust-rotaryjoint can thereby be decreased.

In the exemplary embodiment depicted in FIG. 6, the thrust member is notsecured rigidly to blocking panel 5, but rather is embodied as couplingmember 18 between two joints, so that any relative motion along theelongated hole on lever 3, 11 is eliminated and the thrust-rotary jointitself becomes a rotary joint. This results in a further decrease infrictional losses.

In the exemplary embodiment depicted in FIG. 7, the blocking panel isconfigured as a horizontal panel 5′ having a stamped-out blocking andrelease contour 19, the blocking elements on the shifting links orthrust forks being configured as vertical pins 20, 20′, . . . that canbe arranged in alignment with or at an offset from one another in thelongitudinal direction.

A combination of the basic variant depicted in FIGS. 1-4 with thevariants depicted in FIGS. 5 and 7 is also conceivable.

FIG. 8 shows an exemplary embodiment of a single-rod shifting deviceaccording to the present invention in which lever hub 3 is pin-mountedon central shifting shaft 1. An axial relative motion of centralshifting shaft 1 relative to blocking panel 5 is made possible by anadditional degree of freedom in the thrust-rotary joint. The grooves inlever hub 3 and immobilization pin 2 as shown in FIGS. 1-4 are omittedhere. Articulation stud 21 provided in the thrust-rotary jointcorresponds to approximately twice the shifting travel.

The shifting device according to the present invention allows a greaternumber of shifting links or thrust forks to be locked more securely thanwas possible in the existing art, with no negative effect on function.The number of parts required is small, the configuration of theindividual parts is simple, and manufacturing costs are thus economical.The installation space required is limited because of the location inclose conformity with the central shifting shaft.

The pairings of the locking elements offer good conditions for easydiagonal shiftability, and can be perfectly matched to the requiredselection/shifting smoothness.

Reference Characters

1 Central shifting shaft

2 Immobilization pin

3 Lever hub

4 Entrainment pin

5 Blocking part

6 Guide stud

7 Elongate hole

8 Grooves

9 Thrust member

10 Stud

11 Extension

12 Grooves

13 Cutout

14 Shifting element

15 Blocking element

16 Longitudinal groove

17 Bearing

18 Coupling member

19 Blocking and release contour

20 Pin

21 Articulation stud

What is claimed is:
 1. A single-rod shifting device for a six-speedmotor vehicle manual transmission comprising a central shifting shaft,having fork-shaped shifting elements in the form of shifting links thatengage sliding bushings, and a locking device which, upon shifting ofone of the shifting elements out of the neutral position into a shiftingposition, locks in their neutral positions the shifting elements thatare not to be shifted, wherein the locking device has a lever (3,11)whose rotation point lies on the rotation axis of the axiallydisplaceably mounted central shifting shaft (1) and which is joined toit via a radial entrainment arrangement; and has a blocking part (5)that is arranged immovably with respect to the housing in the shiftingdirection; and has a coupling drive that converts the rotation of thelever (3,11) into a linear motion of the blocking part (5) transverselyto the shifting direction of the central shifting shaft (1); and hasblocking elements (15, 15′ . . . ) on the shifting elements (14, 14′ . .. ) and on the blocking part (5), which are configured in such a waythat upon superposition of said blocking elements in the shiftingdirection, a shifting motion of the shifting elements (14, 14′ . . . )is prevented.
 2. The single-rod shifting device according to claim 1,therein the lever comprises a lever hub (3) and an extension part (11);and the radial entrainment arrangement has a pin (4).
 3. The single-rodshifting device according to claim 1, wherein the blocking part is ablocking part (5) that is mounted, displaceably in the transversedirection with respect to the central shifting shaft (1), on severalguide studs (6) and is equipped with a plurality of cutouts (16, 16′ . .. ).
 4. The single-rod shifting device according to claim 1, wherein theblocking elements (15, 15′ . . . ) arranged on the shifting elements(14, 14′ . . . ) are equipped with longitudinal grooves (8, 8′ . . . )that coact with cutouts (16, 16′) on the blocking part (5).
 5. Thesingle-rod shifting device according to claim 1, wherein the couplingdrive between the blocking part (5) and central shifting shaft (1) is arigid thrust member (9) that, has on its end facing away from theblocking panel a stud (10) extending parallel to the blocking part (5).6. The single-rod shifting device according to claim 1, wherein theextension (11) of the lever hub (3) has on its lower end an elongatehole (7) which the stud (10) of the rigid thrust member of the blockingpart (5) engages.
 7. The single-rod shifting device according to claim1, wherein the lever hub (3) has on the inside diameter at least onecontinuous groove (12, 12′) which engages an entrainment pin (4)arranged transversely to the central shifting shaft (1).
 8. Thesingle-rod shifting device according to claim 1, wherein the couplingdrive between the blocking part (5) and central shifting shaft (1) has athrust-rotary joint having bearing (17).
 9. The single-rod shiftingdevice according to claim 1, wherein the coupling drive between theblocking part (5) and central shifting shaft (1) is embodied as a rotaryjoint (18) that is connected via two joints to the blocking part (5) andthe central shifting shaft (1).
 10. The single-rod shifting deviceaccording to claim 1, wherein the blocking part (5′) is arrangedsubstantially in a horizontal direction and is equipped with astamped-out blocking and release contour (19) into which the blockingelements (20, 20′ . . . ) secured on the shifting elements (14, 14′ . .. ), in the form of vertical pins, engage in alignment with or at anoffset from one another in the longitudinal direction.
 11. Thesingle-rod shifting device according to claim 1, wherein the lever hub(3) is pin-mounted on the central shifting shaft (1); and the axialrelative motion of the central shifting shaft (1) with respect to theblocking part (5) is enabled by way of an additional degree of freedomin the coupling drive configured as a thrust-rotary joint, by means ofan articulation stud (21), provided in the thrust-rotary joint, whoselength corresponds substantially to twice the shifting travel.